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1.
Environ Monit Assess ; 191(8): 517, 2019 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-31352622

RESUMO

The dissipation and residual levels of etoxazole and pyridaben in Goji berry under open field conditions were determined by using GC-NPD (gas chromatography with nitrogen and phosphorus detector) with modified QuEChERS method. At fortification levels of 0.01, 1, and 5 mg/kg in Goji berry, it was shown that recoveries were ranged from 80.40 to 100.9% with relative standard deviation of the method (RSD) for repeatability ranged from 2.20 to 4.25%. The limit of quantification (LOQ) of the method was 0.01 mg/kg. The dissipation rates of etoxazole and pyridaben were described by using first-order kinetics and its half-life, as they are 7.13 days, 5.77 days, and 5.99 days (etoxazole) and 1.02 day, 0.67 day, 1.02 day (pyridaben). The terminal residues of etoxazole and pyridaben were below the European maximum residue limit (MRL, 0.1 mg/kg) in Goji berry when measured 7 days after the final application, which suggested that the use of these insecticides was safe for humans. This study would help in providing the basic information for developing regulation to guard a safe use of etoxazole and pyridaben in Goji berry and prevent health problem from consumers.


Assuntos
Monitoramento Ambiental/métodos , Lycium/metabolismo , Oxazóis/análise , Resíduos de Praguicidas/análise , Piridazinas/análise , China , Meia-Vida , Humanos , Cinética , Lycium/crescimento & desenvolvimento , Oxazóis/metabolismo , Resíduos de Praguicidas/metabolismo , Piridazinas/metabolismo , Tibet
2.
Eur J Med Chem ; 176: 326-342, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31112893

RESUMO

Peroxisome Proliferator-Activated Receptors (PPARs) are ligand-activated transcription factors that govern lipid and glucose homeostasis playing a central role in cardiovascular disease, obesity, and diabetes. These receptors show a high degree of stereoselectivity towards several classes of drugs. This review covers the most relevant findings that have been made in the last decade and takes into consideration only those compounds in which stereochemistry led to unexpected results or peculiar interactions with the receptors. These cases are reviewed and discussed with the aim to show how enantiomeric recognition originates at the molecular level. The structural characterization by crystallographic methods and docking experiments of complexes formed by PPARs with their ligands turns out to be an essential tool to explain receptor stereoselectivity.


Assuntos
Derivados de Benzeno/química , Derivados de Benzeno/metabolismo , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Acetatos/química , Acetatos/metabolismo , Animais , Sítios de Ligação , Cristalografia por Raios X , Humanos , Indóis/química , Indóis/metabolismo , Ligantes , Simulação de Acoplamento Molecular , Oxazóis/química , Oxazóis/metabolismo , Receptores Ativados por Proliferador de Peroxissomo/agonistas , Receptores Ativados por Proliferador de Peroxissomo/antagonistas & inibidores , Receptores Ativados por Proliferador de Peroxissomo/química , Fenilpropionatos/química , Fenilpropionatos/metabolismo , Ligação Proteica , Estereoisomerismo , Relação Estrutura-Atividade , Tirosina/análogos & derivados , Tirosina/metabolismo
3.
Carbohydr Res ; 477: 11-19, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30933786

RESUMO

Enzymatic degradation of locust bean gum provides a Manß(1 → 4)Man disaccharide, which may be converted into the core Manß(1 → 4)GlcNAc disaccharide unit of all N-glycans via conversion to a 2-iodo-glycosyl azide, and Lafont rearrangement. The Manß(1 → 4)GlcNAc disaccharide may be used as a key intermediate for elaboration into more complex N-glycan structures providing a route to N-glycan oxazolines as donor substrates for ENGase enzymes that is considerably shorter than those reported previously.


Assuntos
Galactanos/metabolismo , Mananas/metabolismo , Oxazóis/metabolismo , Gomas Vegetais/metabolismo , Poligalacturonase/metabolismo , Polissacarídeos/metabolismo , Configuração de Carboidratos , Galactanos/química , Mananas/química , Oxazóis/química , Gomas Vegetais/química , Polissacarídeos/química
4.
Chemosphere ; 226: 782-790, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30965249

RESUMO

Etoxazole is a newly registered and widely used acaricide. However, its metabolites were not fully understood and might exhibit similar or even higher toxicity than parent compound. Therefore, in this study, the metabolites of etoxazole in citrus, soil and earthworms were firstly identified by an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS). Four potential metabolites in citrus, 11 in soil, and 8 in earthworms were determined. These metabolites were then further structural elucidated based on the fragment pathways, and accurate mass measurement. The distributions of etoxazole and its main metabolites (M1, M2, M3, M4 and M5) which were identified as the dehydrogenation, hydrolysis, oxidation products of etoxazole (M0) were also monitored in citrus, soil and earthworms at different exposure periods. The 45 days exposure experiment showed that M0 gradually decreased in citrus and soil samples by 80% and 28% of the initial amounts, respectively. In earthworm samples, M0 accumulated in the bodies of the worms during 24 days exposure and then decreased with time. The dissipation rate of etoxazole were citrus > earthworms > soil. Concentrations of M1 and M3 in soil were found continuously increased with time during the experimental period. Moreover, the persistence of M1 in earthworm samples was also observed. Great attention should be paid to these two compounds due to their potential risks to both environmental and human health.


Assuntos
Citrus/metabolismo , Exposição Ambiental , Oligoquetos/metabolismo , Oxazóis/metabolismo , Solo/química , Acaricidas , Animais , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Espectrometria de Massas/métodos , Fatores de Tempo
5.
Nutrients ; 11(3)2019 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-30884817

RESUMO

Mg2+ deficiency may be involved in lifestyle-related diseases, including hypertension, cardiovascular diseases, and diabetes mellitus. Dietary Mg2+ is absorbed in the intestine mediated through transcellular and paracellular pathways. However, there is little research into what factors upregulate Mg2+ absorption. We searched for food constituents that can increase the expression levels of Mg2+ transport carriers using mouse colonic epithelial MCE301 cells. Cyanidin, an anthocyanidin found in black beans and berries, increased the mRNA levels of Mg2+ transport carriers including transient receptor potential melastatin 6 (TRPM6) channel and cyclin M4 (CNNM4). The cyanidin-induced elevation of Mg2+ transport carriers was blocked by GW6471, a peroxisome proliferator-activated receptor α (PPARα) inhibitor, but not by PPARγ, PPARδ, and protein kinase A inhibitors. Cyanidin-3-glucoside showed similar results to cyanidin. Cyanidin increased the protein levels of TRPM6 and CNNM4, which were distributed in the apical and lateral membranes, respectively. The nuclear localization of PPARα and reporter activities of Mg2+ transport carriers were increased by cyanidin, which were inhibited by GW6471. The cyanidin-induced elevation of reporter activity was suppressed by a mutation in a PPAR-response element. Fluorescence measurements using KMG-20, an Mg2+ indicator, showed that Mg2+ influx and efflux from the cells were enhanced by cyanidin, and which were inhibited by GW6471. Furthermore, cyanidin increased paracellular Mg2+ flux without affecting transepithelial electrical resistance. We suggest that cyanidin increases intestinal Mg2+ absorption mediated by the elevation of TRPM6 and CNNM4 expression, and may constitute a phytochemical that can improve Mg2+ deficiency.


Assuntos
Antocianinas/farmacologia , Proteínas de Transporte de Cátions/efeitos dos fármacos , Magnésio/metabolismo , PPAR alfa/efeitos dos fármacos , Compostos Fitoquímicos/farmacologia , Animais , Linhagem Celular , Colo/citologia , Células Epiteliais/metabolismo , Glucosídeos/farmacologia , Mucosa Intestinal/citologia , Deficiência de Magnésio/metabolismo , Camundongos , Oxazóis/metabolismo , RNA Mensageiro/metabolismo , Canais de Cátion TRPM/metabolismo , Tirosina/análogos & derivados , Tirosina/metabolismo , Regulação para Cima
6.
ACS Chem Biol ; 14(4): 674-687, 2019 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-30785725

RESUMO

Environmental and pathogenic microbes produce siderophores as small iron-binding molecules to scavenge iron from natural environments. It is common for microbes to produce multiple siderophores to gain a competitive edge in mixed microbial environments. Strains of human pathogenic Acinetobacter baumannii produce up to three siderophores: acinetobactin, baumannoferrin, and fimsbactin. Production of acinetobactin and baumannoferrin is highly conserved among clinical isolates while fimsbactin production appears to be less common. Fimsbactin is structurally related to acinetobactin through the presence of catecholate and phenolate oxazoline metal-binding motifs, and both are derived from nonribosomal peptide assembly lines with similar catalytic domain orientations and identities. Here we report on the chemical, biochemical, and microbiological investigation of fimsbactin and acinetobactin alone and in combination. We show that fimsbactin forms a 1:1 complex with iron(III) that is thermodynamically more stable than the 2:1 acinetobactin ferric complex. Alone, both acinetobactin and fimsbactin stimulate A. baumannii growth, but in combination the two siderophores appear to compete and collectively inhibit bacterial growth. We show that fimsbactin directly competes with acinetobactin for binding the periplasmic siderophore-binding protein BauB suggesting a possible biochemical mechanism for the phenomenon where the buildup of apo-siderophores in the periplasm leads to iron starvation. We propose an updated model for siderophore utilization and competition in A. baumannii that frames the molecular, biochemical, and cellular interplay of multiple iron acquisition systems in a multidrug resistant Gram-negative human pathogen.


Assuntos
Acinetobacter baumannii/metabolismo , Proteínas de Bactérias/metabolismo , Complexos de Coordenação/metabolismo , Imidazóis/metabolismo , Ferro/metabolismo , Oxazóis/metabolismo , Periplasma/metabolismo , Sideróforos/metabolismo , Acinetobacter baumannii/efeitos dos fármacos , Proteínas de Bactérias/química , Complexos de Coordenação/química , Humanos , Imidazóis/química , Imidazóis/farmacologia , Ferro/química , Estrutura Molecular , Oxazóis/química , Oxazóis/farmacologia , Ligação Proteica , Sideróforos/farmacologia
7.
Methods Mol Biol ; 1946: 259-270, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30798562

RESUMO

Siderophores are high-affinity iron chelators produced and used by bacteria to prosper under iron-limiting conditions they normally encounter in the environment and hosts. In this chapter, we describe the isolation and purification of the siderophores acinetobactin and baumannoferrin produced by the bacterial pathogen Acinetobacter baumannii using XAD-7 batch adsorption and high-pressure liquid chromatography (HPLC). We also describe chemical tests and biological assays used to detect the presence of catechol and hydroxamate siderophores in culture supernatants, XAD-7 extracts, and HPLC fractions.


Assuntos
Acinetobacter baumannii/metabolismo , Imidazóis/química , Imidazóis/isolamento & purificação , Oxazóis/química , Oxazóis/isolamento & purificação , Sideróforos/química , Sideróforos/isolamento & purificação , Catecóis/química , Catecóis/isolamento & purificação , Técnicas de Química Analítica , Cromatografia , Cromatografia Líquida de Alta Pressão , Imidazóis/metabolismo , Oxazóis/metabolismo , Sideróforos/metabolismo
8.
Int J Food Sci Nutr ; 70(2): 212-221, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29962254

RESUMO

Increased superoxide production by phagocytic NADPH oxidase has been associated with inflammatory conditions. Growing evidences suggest that dietary polyphenols may modulate the expression of NADPH oxidase subunits. Herein, we examined whether soluble mate tea (SMT) consumption - a polyphenol-rich beverage - affects the expression of the leukocyte NADPH oxidase protein p47phox and/or circulating biomarkers of inflammation and antioxidant biomarkers in humans. In a two-phase study, nine men were requested to drink water (control) for 8 d and then follow a second 8-d period drinking SMT. Blood samples were analysed for p47phox protein in CD16+/CD14- cells, interleukin (IL)-1ß (IL-1ß), tumour necrosis factor-alpha (TNF-α), IL-6, total phenols, and reduced and oxidised glutathione (GSH and GSSG, respectively) after each study phase. After SMT intake, CD16+/CD14- cells' p47phox protein and serum TNF-α and IL-6 levels were significantly attenuated (P < .05) while plasma phenolic compounds and blood GSH:GSSG ratio were significantly enhanced (P < .05). Consumption of SMT favourably affected leukocytes' p47phox expression and inflammatory cytokine and antioxidants levels in peripheral blood, which may help decrease oxidative stress and low-grade inflammation.


Assuntos
Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Citocinas/sangue , Ilex paraguariensis/química , Inflamação/sangue , Leucócitos/metabolismo , NADPH Oxidases/metabolismo , Adulto , Anti-Inflamatórios/uso terapêutico , Antioxidantes/metabolismo , Antioxidantes/uso terapêutico , Humanos , Inflamação/tratamento farmacológico , Interleucina-6/sangue , Masculino , Oxazóis/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Projetos Piloto , Polifenóis/farmacologia , Polifenóis/uso terapêutico , Valores de Referência , Chás de Ervas , Fator de Necrose Tumoral alfa/sangue , Adulto Jovem
9.
J Cell Biochem ; 120(1): 380-395, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30145828

RESUMO

The effect of Wnt pathway in head and neck cancer could not be elucidated, even though the aberrant Wnt signaling plays a key role in the development of many types of cancer. The inhibitor of ß-catenin responsive transcription (ICRT-3) blocks the Wnt signaling pathway by binding to ß-catenin, which is a coactivator of the Wnt signaling pathway and a promising agent for inhibiting aberrant signaling. In our study, we aimed to evaluate the effect of ICRT-3 on the cytotoxicity, apoptosis, cell cycle progression, migration, and gene expressions in head and neck cancer stem cell (HNCSC) and hypopharynx cancer. The effect of this compound on cytotoxicity and cell viability in FaDu and HNCSC line was assessed by using the water-soluble tetrazolium salt-1 method. The effect of ICRT-3 on apoptosis was detected by using Annexin V and caspase-3, caspase-9 kit, on cell cycle progression by cycle test plus DNA reagent kit, on gene expression by dual luciferase reporter assay, and on migration activity by wound healing assay in both cell lines. ICRT-3 was determined to have cytotoxic and apoptotic effect in both cell lines. In addition, it was also found that the administration of ICRT-3 caused cell cycle arrest and significant decrease in gene expression level and migration ability of the cells.


Assuntos
Citotoxinas/farmacologia , Neoplasias de Cabeça e Pescoço/patologia , Células-Tronco Neoplásicas/metabolismo , Oxazóis/farmacologia , Via de Sinalização Wnt/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Carcinoma de Células Escamosas/patologia , Caspase 3/metabolismo , Caspase 9/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Citotoxinas/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Hipofaríngeas/patologia , Concentração Inibidora 50 , Fator 1 de Ligação ao Facilitador Linfoide/metabolismo , Oxazóis/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fator de Transcrição 4/metabolismo , beta Catenina/antagonistas & inibidores , beta Catenina/metabolismo
10.
Xenobiotica ; 49(1): 13-21, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29299977

RESUMO

1. The utility of 1-aminobenzotriazole (ABT), incorporated in food, has been investigated as an approach for longer term inhibition of cytochrome P450 (P450) enzymes in mice. 2. In rats, ABT inhibits gastric emptying, to investigate this potential limitation in mice we examined the effect of ABT administration on the oral absorption of NVS-CRF38. Two hour prior oral treatment with 100 mg/kg ABT inhibited the oral absorption of NVS-CRF38, Tmax was 4 hours for ABT-treated mice compared to 0.5 hours in the control group. 3. A marked inhibition of hepatic P450 activity was observed in mice fed with ABT containing food pellets for 1 month. P450 activity, as measured by the oral clearance of antipyrine, was inhibited on day 3 (88% of control), week 2 (83% of control) and week 4 (80% of control). 4. Tmax values for antipyrine were comparable between ABT-treated mice and the control group, alleviating concerns about impaired gastric function. 5. Inclusion of ABT in food provides a minimally invasive and convenient approach to achieve longer term inhibition of P450 activity in mice. This model has the potential to enable pharmacological proof-of-concept studies for research compounds which are extensively metabolised by P450 enzymes.


Assuntos
Inibidores das Enzimas do Citocromo P-450/farmacologia , Sistema Enzimático do Citocromo P-450/metabolismo , Triazóis/farmacologia , Administração Oral , Animais , Camundongos , Oxazóis/metabolismo , Pirazóis/metabolismo
11.
Xenobiotica ; 49(8): 895-904, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30215542

RESUMO

1. Vinclozolin (Vin) is a fungicide used in agricultural settings and is classified as an endocrine disruptor. Vin is non-enzymatically hydrolyzed to 2-[[(3,5-dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid (M1) and 3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide (M2) metabolites. There is no information about Vin biotransformation in humans, therefore, the aim of this study was to characterize its in vitro metabolism using human liver microsomes. 2. Vin was metabolized to the [3-(3,5-dichlorophenyl)-5-methyl-5-(1,2-dihydroxyethyl)-1,3-oxazolidine-2,4-dione] (M4) and N-(2,3,4-trihydroxy-2-methyl-1-oxo)-3,5-dichlorophenyl-1-carbamic acid (M7) metabolites, which are unstable and gradually converted to 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutyranilide (DTMBA, formerly denoted as M5). M4 and DTMBA metabolites co-eluted in the same HPLC peak; this co-elute peak exhibited a Michaelis-Menten kinetic, whereas M7 showed a substrate inhibition kinetics. The KM app for co-eluted M4/DTMBA and M7 was 24.2 ± 5.6 and 116.0 ± 52.6 µM, the VMax app was 0.280 ± 0.015 and 0.180 ± 0.060 nmoles/min/mg protein, and the CLint app was 11.5 and 1.5 mL/min/g protein, respectively. The Ki for M7 was 133.2 ± 63.9 µM. Cytochrome P450 (CYP) chemical inhibitors furafylline (CYP1A2), ketoconazole (CYP3A4), pilocarpine (CYP2A6) and sulfaphenazole (CYP2C9) inhibited M4/DTMBA and M7 formation, suggesting that Vin is metabolized in humans by CYP. 3. DTMBA is a stable metabolite and specific of Vin, therefore, it could be used as a biomarker of Vin exposure in humans to perform epidemiological studies.


Assuntos
Desentoxicação Metabólica Fase I , Microssomos Hepáticos/metabolismo , Oxazóis/metabolismo , Inibidores das Enzimas do Citocromo P-450/farmacologia , Humanos , Hidrólise , Masculino , Metaboloma/efeitos dos fármacos , Microssomos Hepáticos/efeitos dos fármacos , Oxazóis/química , Padrões de Referência , Especificidade por Substrato/efeitos dos fármacos
12.
Biotechnol Bioeng ; 116(2): 272-282, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30475394

RESUMO

A great limitation for the usability of free enzymes in organic solvents is their insolubility in these media. Some surfactants are capable of solubilizing enzymes in such media, but they are hard to remove. Covalent modification of enzymes with polymers has led to polymer-enzyme conjugates (PECs) that are soluble in organic solvents, but the process is quite elaborate. Poly(2-oxazoline)s (POx) with the end group 2,2'-imino diacetic acid were shown to form reversible, nano-sized noncovalent aggregates with enzymes. These PECs give clear solutions in organic solvents. The enzymes lysozyme, horseradish peroxidase (HRP), laccase, α-chymotrypsin (CT), catalase, and alcohol dehydrogenase could be solubilized in chloroform and toluene at concentrations of up to 2 mg protein/ml. Laccase, HRP, and CT were shown to survive the transfer into the organic medium and back to water in their active form. The distribution coefficient of the proteins between water and the organic solvent was shown to be dependent on the nature of the POx backbone. All three biocatalysts exhibit greatly enhanced activity in the respective organic solvent.


Assuntos
Enzimas/química , Enzimas/metabolismo , Oxazóis/metabolismo , Solventes/química , Tensoativos/metabolismo , Oxazóis/química , Solubilidade , Tensoativos/química
13.
Elife ; 72018 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-30575522

RESUMO

Crystal structures of peroxisome proliferator-activated receptor gamma (PPARγ) have revealed overlapping binding modes for synthetic and natural/endogenous ligands, indicating competition for the orthosteric pocket. Here we show that cobinding of a synthetic ligand to the orthosteric pocket can push natural and endogenous PPARγ ligands (fatty acids) out of the orthosteric pocket towards an alternate ligand-binding site near the functionally important omega (Ω)-loop. X-ray crystallography, NMR spectroscopy, all-atom molecular dynamics simulations, and mutagenesis coupled to quantitative biochemical functional and cellular assays reveal that synthetic ligand and fatty acid cobinding can form a 'ligand link' to the Ω-loop and synergistically affect the structure and function of PPARγ. These findings contribute to a growing body of evidence indicating ligand binding to nuclear receptors can be more complex than the classical one-for-one orthosteric exchange of a natural or endogenous ligand with a synthetic ligand.


Assuntos
Simulação de Dinâmica Molecular , PPAR gama/química , PPAR gama/metabolismo , Conformação Proteica , Sítios de Ligação , Cristalografia por Raios X , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Humanos , Ligantes , Estrutura Molecular , Oxazóis/química , Oxazóis/metabolismo , Oxazóis/farmacologia , PPAR gama/agonistas , Ligação Proteica , Tiazóis/química , Tiazóis/metabolismo , Tiazóis/farmacologia , Tiazolidinedionas/química , Tiazolidinedionas/metabolismo , Tiazolidinedionas/farmacologia
15.
Elife ; 72018 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-30558715

RESUMO

New strategies are urgently required to develop antibiotics. The siderophore uptake system has attracted considerable attention, but rational design of siderophore antibiotic conjugates requires knowledge of recognition by the cognate outer-membrane transporter. Acinetobacter baumannii is a serious pathogen, which utilizes (pre)acinetobactin to scavenge iron from the host. We report the structure of the (pre)acinetobactin transporter BauA bound to the siderophore, identifying the structural determinants of recognition. Detailed biophysical analysis confirms that BauA recognises preacinetobactin. We show that acinetobactin is not recognised by the protein, thus preacinetobactin is essential for iron uptake. The structure shows and NMR confirms that under physiological conditions, a molecule of acinetobactin will bind to two free coordination sites on the iron preacinetobactin complex. The ability to recognise a heterotrimeric iron-preacinetobactin-acinetobactin complex may rationalize contradictory reports in the literature. These results open new avenues for the design of novel antibiotic conjugates (trojan horse) antibiotics.


Assuntos
Acinetobacter baumannii/metabolismo , Imidazóis/metabolismo , Ferro/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Oxazóis/metabolismo , Precursores de Proteínas/metabolismo , Cristalografia por Raios X , Imidazóis/química , Espectroscopia de Ressonância Magnética , Proteínas de Membrana Transportadoras/química , Oxazóis/química , Ligação Proteica , Multimerização Proteica , Precursores de Proteínas/química , Oligoelementos/metabolismo
16.
J Med Chem ; 61(23): 10502-10518, 2018 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-30457335

RESUMO

Heptaheteroaryl compounds comprised of oxazole and pyridine units (TOxaPy) are quadruplex DNA (G4)-interactive compounds. Herein, we report on the synthesis of parent compounds bearing either amino side chains (TOxaPy-1-5) or featuring an isomeric oxazole-pyridine central connectivity (iso-TOxapy, iso-TOxapy 1-3) or a bipyridine core (iso-TOxabiPy). The new isomeric series showed significant G4-binding activity in vitro, and remarkably, three compounds (iso-TOxaPy, iso-TOxaPy-1, and iso-TOxabiPy) exhibited high antiproliferative activity toward a tumor panel of cancer cell lines. However, these compounds do not behave as typical G-quadruplex (G4) binders, and the kinase profiling assay revealed that the best antiproliferative molecule iso-TOxaPy selectively inhibited Rock-2. The targeting of Rock kinase was confirmed in cells by the dephosphorylation of Rock-2 substrates, the decrease of stress fibers, and peripheral focal adhesions, as well as the induction of long neurite-like extensions. Remarkably, two of these molecules were able to inhibit the growth of cells organized as spheroids.


Assuntos
Desenho de Drogas , Quadruplex G/efeitos dos fármacos , Oxazóis/química , Oxazóis/farmacologia , Piridinas/química , Quinases Associadas a rho/antagonistas & inibidores , Proliferação de Células/efeitos dos fármacos , Células HeLa , Humanos , Ligantes , Oxazóis/metabolismo , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Relação Estrutura-Atividade
17.
Biochemistry ; 57(48): 6653-6661, 2018 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-30406986

RESUMO

The critical role that iron plays in many biochemical processes has led to an elaborate battle between bacterial pathogens and their hosts to acquire and withhold this critical nutrient. Exploitation of iron nutritional immunity is being increasingly appreciated as a potential antivirulence therapeutic strategy, especially against problematic multidrug resistant Gram-negative pathogens such as Acinetobacter baumannii. To facilitate iron uptake and promote growth, A. baumannii produces a nonribosomally synthesized peptide siderophore called acinetobactin. Acinetobactin is unusual in that it is first biosynthesized in an oxazoline form called preacinetobactin that spontaneously isomerizes to the final isoxazolidinone acinetobactin. Interestingly, both isomers can bind iron and both support growth of A. baumannii. To address how the two isomers chelate their ferric cargo and how the complexes are used by A. baumannii, structural studies were carried out with the ferric acinetobactin complex and its periplasmic siderophore binding protein BauB. Herein, we present the crystal structure of BauB bound to a bis-tridentate (Fe3+L2) siderophore complex. Additionally, we present binding studies that show multiple variants of acinetobactin bind BauB with no apparent change in affinity. These results are consistent with the structural model that depicts few direct polar interactions between BauB and the acinetobactin backbone. This structural and functional characterization of acinetobactin and its requisite binding protein BauB provides insight that could be exploited to target this critical iron acquisition system and provide a novel approach to treat infections caused by this important multidrug resistant pathogen.


Assuntos
Proteínas de Bactérias/química , Imidazóis/química , Imidazóis/metabolismo , Proteínas de Ligação ao Ferro/química , Proteínas de Ligação ao Ferro/metabolismo , Ferro/química , Ferro/metabolismo , Oxazóis/química , Oxazóis/metabolismo , Sideróforos/química , Sideróforos/metabolismo , Acinetobacter baumannii/genética , Acinetobacter baumannii/metabolismo , Acinetobacter baumannii/patogenicidade , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Cristalografia por Raios X , Genes Bacterianos , Proteínas de Ligação ao Ferro/genética , Modelos Moleculares , Conformação Proteica
18.
ACS Chem Biol ; 13(12): 3306-3314, 2018 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-30371052

RESUMO

The methyl substituents in products of trans-acyltransferase assembly lines are usually incorporated by S-adenosyl-methionine (SAM)-dependent methyltransferase (MT) domains. The gem-dimethyl moieties within the polyketide disorazol are installed through the iterative action of an MT in the third module of its assembly line. The 1.75-Å-resolution crystal structure of this MT helps elucidate how it catalyzes the addition of two methyl groups. Activity assays of point mutants on ß-ketoacyl chains linked to an acyl carrier protein and N-acetylcysteamine provide additional insights into the roles of active site residues. The replacement of an alanine with a phenylalanine at an apparent gatekeeping position resulted in more monomethylation than dimethylation. MTs may form an interface with ketoreductases (KRs) and even mediate the docking of trans-acyltransferase assembly line polypeptides through this association.


Assuntos
Metiltransferases/química , Policetídeo Sintases/química , Oxirredutases do Álcool/química , Oxirredutases do Álcool/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Domínio Catalítico/genética , Cristalografia por Raios X , Metilação , Metiltransferases/genética , Metiltransferases/metabolismo , Modelos Moleculares , Estrutura Molecular , Mutação , Myxococcales/enzimologia , Oxazóis/química , Oxazóis/metabolismo , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo , Policetídeos/química , Policetídeos/metabolismo , Ligação Proteica , Domínios Proteicos , Alinhamento de Sequência
19.
J Med Chem ; 61(22): 10333-10339, 2018 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-30365311

RESUMO

A recently reported potent inhibitor of enterovirus 71 3C protease, ( R)-1, was found to have stability and potential toxicity issues due to the presence of a cyanohydrin moiety. Modifying the labile cyanohydrin moiety, by serendipity, led to the discovery of 4-iminooxazolidin-2-one-based inhibitors 4e and 4g with potent inhibitory activity and significantly improved stability. In vivo pharmacokinetic studies of 4e also demonstrated high plasma exposure and moderate half-life. These compounds have shown potential of becoming anti-EV71 drug candidates.


Assuntos
Inibidores de Cisteína Proteinase/química , Inibidores de Cisteína Proteinase/farmacologia , Enterovirus Humano A/enzimologia , Nitrilos/química , Oxazóis/química , Oxazóis/farmacologia , Proteínas Virais/antagonistas & inibidores , Animais , Cisteína Endopeptidases/química , Cisteína Endopeptidases/metabolismo , Masculino , Camundongos , Simulação de Acoplamento Molecular , Oxazóis/metabolismo , Conformação Proteica , Proteínas Virais/química , Proteínas Virais/metabolismo
20.
J Nat Prod ; 81(9): 2106-2110, 2018 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-30130105

RESUMO

The production of two new heterocyclic peptide isomers, catenulobactins A (1) and B (2), in cultures of Catenuloplanes sp. RD067331 was significantly increased when it was cocultured with a mycolic acid-containing bacterium. The planar structures and absolute configurations of the catenulobactins were determined based on NMR/MS and chiral-phase GC-MS analyses. Catenulobactin B (2) displayed Fe(III)-chelating activity and moderate cytotoxicity against P388 murine leukemia cells.


Assuntos
Micromonosporaceae/metabolismo , Ácidos Micólicos/análise , Oxazóis/metabolismo , Peptídeos/metabolismo , Animais , Quelantes/química , Quelantes/isolamento & purificação , Quelantes/metabolismo , Quelantes/farmacologia , Leucemia P388/tratamento farmacológico , Leucemia P388/patologia , Espectroscopia de Ressonância Magnética , Camundongos , Oxazóis/química , Oxazóis/isolamento & purificação , Oxazóis/farmacologia , Peptídeos/química , Peptídeos/isolamento & purificação , Peptídeos/farmacologia
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